Dehalogenases: environmental defence mechanism and model of enzyme evolution

Studies on the fate of halogenated organic compounds in the environment from the 1950s onwards have led to the conclusion that the main method of degradation of these compounds is via microbial metabolism. and that this is mediated by enzymes which remove the halogen substituents. The enzymes are called dehalogenases. The study of these enzymes has yielded much useful information about the evolution of catabolic enzymes in general and represents an ideal tool for the investigation and illustration of many key concepts in enzymology including parallel evolution, convergent evolution, gene transfer, determination of reaction mechanisms and structure-activity relationships. This review summarises the key principles of microbial dehalogenation and illustrates the applications that these studies may have in teaching more generalised enzymological concepts. (C) 1998 IUBMB. Published by Elsevier Science Ltd. All rights reserved.